Electrolysis Flashcards
conduct electricity when molten or aqueous.
Ionic compounds
When an electric current passes through such compounds, the compounds are decomposed in a chemical reaction. This
is known as
electrolysis
The ionic compound is called an
electrolyte
*The electrode attached to the positive terminal of the cell.
*Anions are attracted to it.
Anode
*The electrode attached to the negative terminal of the cell.
*Cations are attracted to it.
Cathode
are usually made of carbon or platinum, as they are
unreactive or inert.
Electrodes
take electrons from the cathode to become lead
atoms (reduction).
lead ions (At the cathode)
s donate electrons to the anode to become
bromide molecules (oxidation).
At the anode
The bromide ions
are attracted to the anode
Bromide ions
are attracted to the cathode
Lead ions
move near to cathode
Lead ions
move near to anode
Bromide ions
take electrons from the electrode to become
hydrogen atoms (reduction).
At the cathode
The hydrogen ions
There are two anions in the electrolyte:
hydroxide and chloride ions
from the electrolyte are discharged if they are chloride, bromide or iodide ions. For sulphates and nitrates, oxygen from water is discharged
Negative ions
from the electrolyte that are below Ni2+(aq) in the electrochemical (or reactivity) series are discharged at the
negative cathode.
Positive ions
If the positive ions are those of reactive metals above Ni2+(aq)
(e.g.. Na+, K+ and Ca2+), hydrogen gas from water is
discharged
Anions
K+ (aq)
Na+ (aq)
Ca2+ (aq)
Mg2+ (aq)
Zn2+ (aq)
Fe2+ (aq)
Pb2+ (aq)
H+ (aq)
Cu2+ (aq)
Ag+ (aq)
Cations
SO4
2-
(aq)
NO3
-
(aq)
Cl -
(aq)
Br -
(aq)
I -
(aq)
OH -
(aq)
SO4
2-
(aq)
The decomposition of a substance by electricity is
called
electrolysis
is an ionic compound, in the molten or aqueous state, that conducts electricity and is decomposed by the current
electrolyte
The rods through which the direct current enters and
leaves the cell are known as
electrodes
are usually inert.
Electrodes
is the electrode which is connected to the positive terminal of a cell. Anions are attracted to it. Oxidation occurs at the anode
anode
is the electrode connected to the negative terminal of the cell. Cations are attracted to the cathode. Reduction occurs at this electrode.
cathode
When a molten electrolyte is electrolysed,
*a metal (from the positive ions) is discharged at the cathode.
*a non-metal (from the negative ions) is discharged at the anode.
When a aqueous electrolyte is electrolysed
*the products come from either the electrolyte or water present.
*The product at the cathode is a metal or hydrogen gas.
*The product at the anode is a non-metal
are not discharged at the cathode. Instead, hydrogen from water is evolved
Reactive metals
are not discharged at the anode. Instead, oxygen from water is produced.
Sulphate and nitrate ions
